Recent releases are not signed

[clokep]

It seems that recent releases of Synapse are not being signed any longer. I think this is due to the release script not properly signing the tags, but I'm unsure.

(Note that @anoadragon453 mentioned he has been doing the tags manually so his releases do have signatures on them.)

@erikjohnston mentioned this might be due to already having the necessary keys unlocked or not.

[erikjohnston]

We probably need to add an option to:

synapse/scripts-dev/release.py

Line 279 in 6878e10

repo.create_tag(tag_name, message=changes)

The docs for the github lib is at https://pygithub.readthedocs.io/en/latest/reference.html git lib is at https://gitpython.readthedocs.io/en/stable/